New Wallaby-Sized Dinosaur Emerges from Gippsland

Millions of years before wallabies evolved, a wallaby-sized dinosaur was grazing prehistoric herbage in a long-vanished valley between the continents we call Australia and Antarctica. Newly identified from fossils in 125 million-year-old rocks by Dr Matt Herne of the University of New England, Galleonosaurus dorisae ran upright on powerful hind legs in the vast forested floodplain of the rift valley between the continents that were slowly tearing apart.

Herne and his colleagues identified the dinosaur from five fossilised upper jaws found in rocks from Bunurong Marine Park in the Gippsland region of Victoria. Unusually, the fossilised jaws include young to mature individuals, which Herne said was “the first time an age range has been identified from the jaws of an Australian dinosaur”.

Galleonosaurus is the fifth small-bodied ornithopod dinosaur named from Victoria. This diversity of ornithopod, not seen anywhere else in the world, paints a picture of an environment especially hospitable to these small dinosaurs.

At the time of Galleon­osaurus, sediments from a 4000 km long chain of large, actively erupting volcanoes along the eastern margin of the Australian continent were carried westward by large rivers into the Australian–Antarctic rift valley, where they formed deep sedimentary basins. As sediment washed down the rivers they picked up and eventually encased the bones of dinosaurs and other vertebrates, along with fallen trees.

Herne’s discovery, which has been published in the Journal of Paleontology (https://goo.gl/qoMRJj), revealed that Victoria’s ornithopods were closely related to those found in Patagonia. “We are steadily building a picture of terrestrial dinosaur interchange between the shifting Gondwanan continents of Australia, South America and Antarctica during the Cretaceous period,” he said.